ES2265889T3 - RESONANT DEVICE, SUCH AS BEAT OR GENERATOR EFFORT. - Google Patents

Abstract

The invention relates to a generator of dynamic loads comprising a main mass/spring system composed of a main mass comprising at least one main mass element of mass M2 and of at least one main spring element of stiffness K2. The device is one which comprises an additional mass/spring system, which is coupled to the main mass/spring system and which is composed of an additional mass of mass m3 and of at least one additional spring element of stiffness K3, the assembly exhibiting a first and a second resonant frequency f0 and f2 respectively, and an anti-resonant frequency f1, with f0<f1<f2.

Description

Resonant device, such as whisk or stress generator

The present invention aims at a resonant device comprising a system of spring mass that associates a main mass and a spring, usable as passive or active beater tuned for suffocate a vibration, or as a stress generator dynamic to apply efforts to a structure. A device liability that is arranged in parallel with a main suspension subject to vibrations is known from JP 57186651.

Tuning is obtained by choosing the mass and the stiffness of the spring so that for example the proper frequency of the mass-spring assembly is equal to that of the vibration to be generated or suffocate.

An adaptation between the device and the or Vibrations to suffocate pose a certain number of problems. One of these problems is that, for known devices, the Tuning frequency is fixed, and that the device cannot therefore to be used rather than for operation at a given frequency

According to a first aspect, the present invention It is aimed at allowing a frequency adjustment of the device.

With this aim, the invention relates to a passive or active resonant device comprising a system of spring mass composed of a main mass that it comprises at least one main mass element and for at least one spring element characterized in that it comprises at least one mass additional comprising at least one additional mass element and a coupling device suitable for coupling additional mass to the main mass and decouple it to modify the frequency of Device tuning

The device can be characterized because It comprises at least one electromagnetic assembly comprising two complementary devices, of which the first presents the least one electromagnetic piece and the second one has at least one electromagnet, one of the two complementary devices being coupled to the main mass, and the other device being complementary coupled to an additional mass, the two being devices arranged in front of each other, so that this mode, when one of the electromagnets is activated, two complementary devices are mechanically supportive, of so that the main mass and said additional mass are coupled.

At least one electromagnetic part can be coupling, for example, elastically to the main mass, being then, at least one electromagnet coupled to said additional mass. Said elastic coupling, which is for example made with the help of a flexible sheet, can present a degree of freedom elastic in a direction substantially perpendicular to a main direction of the oscillations of the main mass, by example the direction of effort generation.

The device can be characterized because a first complementary device comprises two pieces electromagnetic spaced from each other and in solidarity with said flexible sheet, and because a second complementary device comprises two electromagnets arranged facing the two pieces electromagnetic The two electromagnets can be integral to minus a connection piece.

At least one additional mass can be kept in position by an elastic device that has a degree of elastic freedom in a direction substantially parallel to a main direction of the oscillations of the main mass, presenting this device for example at least one sheet elastic

Another problem of technical devices previous is, that once a frequency has been chosen, it is difficult to master the amplitude of the oscillations of an active beater also called dynamic stress generator that can, near of the resonance become very large and lead to saturation, even to the destruction of an actuator that produces such dynamic efforts

Another problem of technical devices previous is that it is difficult to convey dynamic efforts important.

According to a second aspect, the present invention allows a good domain of the amplitude of the oscillations and / or authorizes the transmission of important efforts.

To this end, the invention proposes a generator of dynamic efforts comprising a system of main spring mass composed of a mass main comprising at least one main mass element of mass m2 and at least one spring element of stiffness K2, characterized in that it comprises a system of auxiliary spring-mass that is coupled to the system main spring mass and which is composed of a auxiliary mass of mass m3 and at least one spring element K3 rigidity auxiliary, presenting the set a first and a second resonance frequency, referenced respectively f_ {0} and f_ {2}, and an antiresonance frequency f_ {1}, with f_ {0} <f_ {1} <f_ {2}. The generator can work especially at the frequency f_ {0} and / or at the frequency f_ {1}, for example with the help of an excitation device for drive the generator between resonances f_ {0} and f_ {2} and especially at the frequency of antiresonance f_ {1}.

In general, the generator can work Especially at any frequency. Its use is not limited to frequencies f_ {0}, f_ {1}, f_ {2}, but then it is not exploited the anti-resonance characteristic at frequency f_ {1}.

The interest of frequency operation f_ {1} = (or near it) is that it allows operation to reduced amplitude, which makes it virtually impossible mechanically saturate the actuator while obtaining Always benefit from mechanical amplification. Being the only one limitation, the maximum intensity allowed by the generator, is possible to generate significant efforts that can be transmitted to a structure.

In addition, it is possible to vary the frequencies mentioned above and in particular the frequencies f_ {0} and f_ {1}, adding at least one additional mass that can be coupled or decouple from the main mass, according to the first aspect of the invention, according to various embodiments above mentioned.

Other features and advantages of the invention they will appear better in the following description, given as non-limiting example, in connection with the attached drawings, in the which:

- Figure 1 represents a device that it comprises a mass-spring system usable in the framework of the present invention;

- figure 2 represents an embodiment preferred relative to the first aspect of the invention, and that can be also use within the framework of the second aspect of the invention;

- Figure 3 is a side view of the device according to figure 2;

- figure 4 represents an embodiment preferred of an additional mass module.

- Figure 5 represents a mass device ferromagnetic, usable to couple an additional mass;

- Figure 6 illustrates a device according to the second aspect of the invention, whose response curves are represented in figure 7.

The device represented in figure 1 it comprises a mass element 1 of mass m3 which, in the case of a active whisk, integrates an electrodynamic generator or variable reluctance. A plate 5 fixed to the element 1 carries in its ends two springs 3 that confer on the system of spring mass thus constituted a stiffness K3. These two springs 3 rest on cylindrical blocks 31 carried by a plate 2 that is coupled to a structure of which they want to quench the vibrations or to which they want to communicate vibrations

At the top, plate 5 carries a plate 6 at whose ends the branches 81 of two springs 8 are fixed which they have two opposite branches 81 and 83 separated by a slot 82 and connected to each other by sectors 85. At the bottom, the element 1 has a plate 7 whose bottom is mounted a plate 6 at whose ends the branches 91 of two springs 9 similar to springs 58 and having two branches opposite 91 and 93 separated by a slit 92 and connected by sectors 95. Branches 83 and 93 of springs 8 and 9 are in solidarity to uprights 84 perpendicular to the plane of the plate 2 and which are solidarity with this one. Plates 6 being in solidarity with plate 5 and a stage 7, springs 8 and 9 allow centering the set of 1-spring 3 mass during travel perpendicular to the plane of stage 2.

The uprights 84 can be used to arrange additional doughs that can be attached to the main dough 1 or decouple it, to vary the dynamic mass of the beater, and therefore modify the resonance conditions.

As shown in Figure 4, a module 10 of additional mass to add a mass m4 to the main mass m3 it comprises two electromagnets 102 mounted on the two ends of the connection arm 110 and 111, cut in 112 for the passage of a stile 84. Springs 115 having arms 16, form a zigzag path, which are separated by slits 117 that are extend from opposite edges 113 and 119. These springs 115 they serve to suspend and guide the mass m4 that is constituted by the two electromagnets 102 and the connecting parts 110 and 111.

Each spring 115 is mounted on two pairs of braces 101 and 103. Braces 101 are integral to a fixed plate 120 fixed by its opening 125 to the post 84. The braces 103, mounted in opposition to the braces 101, are integral to the corresponding electromagnet 102. For each electromagnet, there are two upper and lower pairs of braces 101, and two upper pairs e lower brace 103. In this way a degree of freedom parallel to the direction of travel of element 1, that is, perpendicular to the plane of the plate 2.

Figure 5 shows the device 20 that allows the additional mass m4 (ref. 10) to be coupled to the main mass 3. It comprises two ferromagnetic masses 204 for example laminated mounted at the end of a flexure sheet 201 fixed on its openings 202 on a side face of the plate 7. This sheet of flexion has a great rigidity in the direction of travel of the mass 1 of the beater, that is, of the vibration that must be generate or attenuate, but a much reduced stiffness in the plane perpendicular to said direction of travel.

As shown in Figure 2, the masses ferromagnetic 204 are located in front of the electromagnets 102. In this way, the magnetic circuits of the electromagnets 102 they close on the magnetic masses 204.

The coupling is made as follows way: activation of electromagnets 102 causes application of the masses 204 on the surface of the electromagnets 102 and by therefore a mechanical coupling of the additional mass. Given that the plate 7 is solidarity in displacement to the main mass, the additional mass is also dragged in a parallel motion to axis of the uprights 84, which becomes impossible due to the effect of suspension provided by laminar springs 115.

When electromagnets 102 are deactivated, the masses 204 are separated from the electromagnets 102 and the mass additional is decoupled from the main mass.

The realization of figures 2 to 5 allows make a variation of the batter's mass by coupling one or several additional masses of precise values, which allows to change the frequency of the beater to treat vibrations whose frequency can change.

In the example shown, they are excited simultaneously the four electromagnets to couple the two modules 10 of item 1.

The mass number can be added in this way you want and give the beater so many new frequencies of tuning.

Fixing of additional masses It allows:

-

by one part, when they are not coupled to the main mass, which remain in front of the bending sheet attached to the mass of the whisk along its entire path,

-

by other part, follow the movement of the main mass in mode connected.

This result is obtained thanks to the springs of sheets 115 that are sufficiently rigid in the plane perpendicular to the direction of the beater movement to avoid its movement in this plane and sufficiently flexible in the direction of the beater movement to accompany it in its displacements, with the flexibility set to perform with the new dough and the previous characteristics of the whisk the new Miso tuning. The stiffness of these sheets can be complement those of the springs acting in parallel with them to perform the new tuning (i.e. connect to initial beater a new beater placed in parallel).

According to the second aspect of the invention, the device allows to generate significant dynamic efforts at low frequency according to a setpoint provided to a box electronics.

The effort is generated inertially, it is say, using the action-reaction principle which is applied to a mass excited in effort. The dough is constituted by the mass of the generator body.

The invention can be carried out with the help of a variable reluctance generator incorporated into the main mass 1 and with the help of your journey through a digital calculator whose algorithm linearizes in a manner known per se, the characteristic force-displacement, both as a generator of effort and mass in a mass-spring system to introduce significant efforts at low frequency in a structure.

When looking to generate an effort on a structure S any without relying on another structure, the basic principle is to rely on a reaction mass m2. The magnetic stress U created between the structure and the mass m2 generates an effort Ft in structure S. This effort is connected to U by the relation Ft = H.U where U is a function of transfer given by the mounting characteristics of the generator:

H (p) = m2p2 / (m2p2 + K2)

P is the Laplace variable.

K2 designates the stiffness of the elastic connection between mass m2 and structure S.

In general the mass m2 is constituted by the moving mass of an electromagnetic generator (reluctance variable) or of an electrodynamic generator.

The mass m2 and the elastic stiffness connection K2 it constitutes an oscillating mechanical system from which it can be exploited resonance amplification at the limit of displacements admissible

This technique is currently used with electrodynamic generators (coils that are submerged in a field constant).

However, this technique that uses Electrodynamic generators is difficult to apply when looking for high Ft transmitted stress levels (typically greater than 1 kN), since it would lead to a mass and volume prohibitive of permanent magnets creators of the field magnetic.

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The direct use of the generators of variable reluctance that provide significant efforts in a volume, and then reduced is very little possible to low frequency, since its travel is limited by the need of having small air gaps to generate effort.

The solution is obtained by exciting a system oscillating mass-spring at a frequency close to your own frequency Then you take advantage of the coefficient of amplification of such a system, without having to generate a important initial effort.

The assembly scheme (see figure 6) applies a generator that has a m2 suspended mass with a stiffness K2, which excites the mass m3 of the auxiliary spring-mass system, which has an auxiliary mass m3 and has a stiffness K3.

The mass m2 is constituted by the mass main 1 that is coupled to a generator of which constitutes the moving mass The stiffness K2 is defined by the springs 3.

Designating with Z_ {2} the amplitude of the movement of mass m2 with respect to mass m3, you have:

Z_ {2} / U = [(m2 + m3) p2 + K3)] / [m2.m3.p4 + (K2.m2 + m2.K3 + K2.m3) p2 + K2.K3]

quad

Ft / U = -K3.m2.p2 / [m2.m3.p4 + + (K2.m2 + m2.K3 + K2.m3) p2 + K2.K3],

which allows to determine the three frequencies own f_ {0}, f_ {1} and f_ {2} that are attached to the parameters mass and stiffness by the following formula:

f_ {0} = \ 1/4 \ \ Pi \ (m2.K2 + K2.m3 + K2.m2 - \ sqrt {\ Delta}

f_ {1} = \ ^ 1/2 \ \ Pi \ sqrt {K3 / (m2 + m3)}

f_ {2} = \ 1/4 \ \ Pi \ (m2.K3 + K2.m3 + K2.m2 + \ sqrt {\ Delta}

Δ = (m2 2 .K3 2 - 2m2.m3.K2.K3 + 2m2 2 .K3.K2 + K2 2 .m3 2 + 2K2 2 .m3.m2 + k2 2 .m2 2) / (m2.m3)

These formulas are translated by graphic representations given in figure 7 with the following values:

K3 = 2.2 10 5 \ N / m

m3 = 4 kg

K2 = 1.518 10 6 \ N / m

m3 = 13.7 kg

The above curve presents the module of the Ft / U transfer function, the middle curve presents the module of the transfer function Z_ {2} / U, the curve below represents the phase of the transfer function Z2 / U.

The device has two frequencies of resonance f_ {0} and f_ {2} for which there is a large amplification of the generated effort, and a frequency of antiresonance f1 corresponding to the own mode of the masses m2 + m3 over spring k3.

How do you want to generate low efforts frequency, you can adjust the masses and rigidities for this resonant frequency mode f0 or f1 be that of the utilization.

If the effort generator is governed to the frequency f_ {0}, it is seen that the amplitude z_ {2} can become very large and lead to saturation, even the destruction of actuator On the contrary, it is observed that this amplitude becomes very small around the antiresonance f_ {1}, in the case of a reluctance generator, this amplitude Z_ {2} is the variation of air gap, which makes it possible to therefore use a small air gap and therefore have a generated effort important.

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If governed at the frequency f_ {1}, the fact having a small z_ {2} offset leads to using the variable reluctance actuator for the reason indicated above. By therefore it is almost impossible to mechanically saturate the actuator since z_ {2} remains very small whatever U. The limitation of use is no longer due to always difficult resonance to control, but at the maximum intensity allowed by the generator.

At this frequency, the Ft / U ratio is always greater than 1, which still makes use of amplification mechanics.

Therefore it is at the frequency f_ {1} that must generate the effort Ft transmitted to the structure more important. Its value depends essentially on the maximum intensity of the current to be circulated in the windings of the variable reluctance generator.

To ensure that the 3 frequencies f_ {0}, f_ {1}, f_ {2} respect the relationship f_ {2}> f_ {1}> f_ {0}, we must choose the masses and rigidities such that:

f_ {1} is given as the frequency of the maximum of Ft searched for f_ {2} = k.f_ {1} with k> 1, ideally 2 <k <4, given m2, k2 \ approxm2 (2 \ Pi.f_ {2}) 2, (this value has been calculated in mode decoupled, which gives a result in a first approximation overestimated that can be corrected manually below).

Then you have K3 = (m2 + m3) (2 \ Pi.f_ {2}) 2, m3 being a mass linked to the mechanical construction (actuator housing, ½ mass of K3 and K2 ...). For a maximum Ft effort at a given total mass, you have interest in maximizing m2 with respect to (m2 + m3).

Respecting these relationships, you will have naturally f_ {0} <f_ {1.}

The generator is preferably of the type of variable reluctance with an auxiliary moving mass of m2 value, the main mass being adjusted to the m3 value.

Reed springs that have flexibility elevated in the direction of the desired vibrations, and rigid in the Other directions allow guiding the mass m2. It can be done for this purpose use a mounting of the same type as for the additional mass m4.

It is noted, however, that another type of guidance could be used since the eventual damping that could introduce would be less annoying than for a system that works at the frequency resonance f0, since at the frequency of antiresonance f1, the amplification coefficient is low modified by eventual damping while it is Much to resonance.

Claims (9)

1. Dynamic force generator comprising a main mass-spring system composed of a main mass comprising at least one main mass element of mass m2 and at least one main spring element of stiffness K2, characterized in that it comprises a system of auxiliary spring-mass that is coupled to the main mass-spring system and which is composed of an auxiliary mass of mass m3 and at least one auxiliary spring element of stiffness K3, the assembly having a first and a second resonance frequency, respectively f_ {0} and f_ {2}, and an antiresonance frequency f_ {1}, which corresponds to the mode of the main mass element and the auxiliary mass (mass m2 + m3) on the auxiliary rigidity spring k3, with f_ {0} <f_ {1} <f_ {2}, and because it comprises an excitation device (1) for operating the generator at least at said anti-resonance frequency f_ {1}. 2. Generator according to claim 1, characterized in that the excitation device (1) is of the variable reluctance type. 3. Generator according to one of the preceding claims, characterized in that it comprises at least one additional mass (10) comprising at least one additional mass element (102) and a coupling device (204) suitable for coupling the additional mass (10) to the main mass (1) and decouple it, to modify the generator frequency. 4. Generator according to claim 3, characterized in that the device comprises an electromagnetic assembly comprising two complementary devices, of which the first has at least one electromagnetic part (204) and the second has at least one electromagnet (102), one being of the two complementary devices coupled to the main mass (1), and the other complementary device being coupled to an additional mass (10), the two devices being arranged opposite each other, so that, when said an electromagnet ( 102) is activated, said two complementary devices (102, 104) are mechanically integral, so that the main mass (1) and said additional mass (10) are coupled. 5. Generator according to claim 4, characterized in that at least one electromagnetic part (204) is coupled to the main mass (1), and because at least one electromagnet (102) is coupled to said additional mass (10). 6. Generator according to claim 5, characterized in that the coupling between said electromagnetic part (204) and the main mass (1) is elastic. 7. Generator according to claim 6, characterized in that said coupling has a degree of elastic freedom in a direction substantially perpendicular to a main direction of dynamic force generation. 8. Generator according to one of claims 6 or 7, characterized in that said elastic coupling is made of at least one flexible sheet (202). 9. Generator according to one of claims 3 or 8, characterized in that at least one additional mass (102) is held in position by an elastic device (115) having a degree of elastic freedom in a direction substantially parallel to a main direction of Dynamic effort generation.